19 July 2007

Alaskan glaciers, and the snows of Kilimanjaro

My parents recently got back from a two-week trip to Alaska.

While in Alaska, they saw some glaciers. I remembered that in An Inconvenient Truth, Al Gore mentioned how some glaciers in the Alps have retreated quite a bit within the historical record, showing pictures from the late 19th century and comparing them to modern-day photographs. It turned out that some of the glaciers there have receded within the memory of the people who live there, but others have actually advanced.

It seems to me that the only way to know for sure if global warming is causing glaciers to retreat is to analyze a large number of them for which there is a historical record. (Although I'm not a climatologist, the Alps seem like the best site for such a study simply because people have been living there for quite some time.) Anecdotal evidence just isn't valid here. However, it seems like there are better ways of tracking temperature than looking at glaciers (for example, just looking at actual temperature numbers!) and so the glaciers are more a convenient symbol than anything, because miles-long ice formations seem like something that humans just couldn't possibly melt! What one person knows is simply an inadequate sample, although it can make for a powerful story.